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-- Copyright 2006-2017 Mitchell mitchell.att.foicica.com. See LICENSE.
-- Markdown LPeg lexer.
local l = require('lexer')
local token, word_match = l.token, l.word_match
local P, R, S = lpeg.P, lpeg.R, lpeg.S
local M = {_NAME = 'markdown'}
-- Whitespace.
local ws = token(l.WHITESPACE, S(' \t')^1 + S('\v\r\n')^1)
-- Block elements.
local header = token('h6', l.starts_line('######') * l.nonnewline^0) +
token('h5', l.starts_line('#####') * l.nonnewline^0) +
token('h4', l.starts_line('####') * l.nonnewline^0) +
token('h3', l.starts_line('###') * l.nonnewline^0) +
token('h2', l.starts_line('##') * l.nonnewline^0) +
token('h1', l.starts_line('#') * l.nonnewline^0)
local blockquote = token(l.STRING,
lpeg.Cmt(l.starts_line(S(' \t')^0 * '>'),
function(input, index)
local _, e = input:find('\n[ \t]*\r?\n',
index)
return (e or #input) + 1
end))
local blockcode = token('code', l.starts_line(P(' ')^4 + P('\t')) * -P('<') *
l.nonnewline^0)
local hr = token('hr', lpeg.Cmt(l.starts_line(S(' \t')^0 * lpeg.C(S('*-_'))),
function(input, index, c)
local line = input:match('[^\n]*', index)
line = line:gsub('[ \t]', '')
if line:find('[^'..c..']') or #line < 2 then
return nil
end
return (input:find('\n', index) or #input) + 1
end))
-- Span elements.
local dq_str = token(l.STRING, l.delimited_range('"', false, true))
local sq_str = token(l.STRING, l.delimited_range("'", false, true))
local paren_str = token(l.STRING, l.delimited_range('()'))
local link = token('link', P('!')^-1 * l.delimited_range('[]') *
(P('(') * (l.any - S(') \t'))^0 *
(S(' \t')^1 *
l.delimited_range('"', false, true))^-1 * ')' +
S(' \t')^0 * l.delimited_range('[]')) +
P('http://') * (l.any - l.space)^1)
local link_label = token('link_label', l.delimited_range('[]') * ':') * ws *
token('link_url', (l.any - l.space)^1) *
(ws * (dq_str + sq_str + paren_str))^-1
local strong = token('strong', (P('**') * (l.any - '**')^0 * P('**')^-1) +
(P('__') * (l.any - '__')^0 * P('__')^-1))
local em = token('em',
l.delimited_range('*', true) + l.delimited_range('_', true))
local code = token('code', (P('``') * (l.any - '``')^0 * P('``')^-1) +
l.delimited_range('`', true, true))
local escape = token(l.DEFAULT, P('\\') * 1)
local list = token('list',
l.starts_line(S(' \t')^0 * (S('*+-') + R('09')^1 * '.')) *
S(' \t'))
M._rules = {
{'header', header},
{'list', list},
{'blockquote', blockquote},
{'blockcode', blockcode},
{'hr', hr},
{'whitespace', ws},
{'link_label', link_label},
{'escape', escape},
{'link', link},
{'strong', strong},
{'em', em},
{'code', code},
}
local font_size = 10
local hstyle = 'fore:red'
M._tokenstyles = {
h6 = hstyle,
h5 = hstyle..',size:'..(font_size + 1),
h4 = hstyle..',size:'..(font_size + 2),
h3 = hstyle..',size:'..(font_size + 3),
h2 = hstyle..',size:'..(font_size + 4),
h1 = hstyle..',size:'..(font_size + 5),
code = l.STYLE_EMBEDDED..',eolfilled',
hr = l.STYLE_DEFAULT..',bold',
link = 'underlined',
link_url = 'underlined',
link_label = l.STYLE_LABEL,
strong = 'bold',
em = 'italics',
list = l.STYLE_CONSTANT,
}
-- Embedded HTML.
local html = l.load('html')
local start_rule = token('tag', l.starts_line(S(' \t')^0 * '<'))
local end_rule = token(l.DEFAULT, P('\n')) -- TODO: l.WHITESPACE causes errors
l.embed_lexer(M, html, start_rule, end_rule)
return M
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